This is Core B of the Program "Combinatorial Approaches for Novel Anti- cancer Agents," a multidisciplinary effort to employ chemical diversity, high throughput and smart assays to anti-tumor drug discovery. In this Core, computational chemistry and chemical data base management will be used to analyze the structure-activity relationships of synthetic combinatorial libraries of phosphatase inhibitors and anti-tubulin compounds, leading to both mechanistic and structural insights for the optimization of anti-cancer chemotherapeutic activity. This strategy will allow for the identification and comparison of the structural and physicochemical features required for in vitro cell-free biochemical, in vitro tumor cell line, and in vivo anti-tumor activity. During the Program, Core B will build and utilize hierarchical SAR/QSAR models pertaining to the individual molecular targets, anti-proliferative activity towards cancer cell lines, and activity towards solid tumors. These activities will be optimized in order to discover selective, highly efficacious, pre-clinical chemotherapeutic agents with anti-tumor activity.